Express VI Created by Code Generation Feature in LabVIEW SignalExpress

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Express VI Created by Code Generation Feature in LabVIEW SignalExpress

Primary Software: LabVIEW Signal Express>>Development System
Primary Software Version: 3.0
Primary Software Fixed Version: N/A
Secondary Software: N/A

Problem:
I have a working LabVIEW SignalExpress project. I would like to generate LabVIEW code for this project by selecting Tools»Generate Code»LabVIEW Diagram in LabVIEW SignalExpress. When I do this, I get a LabVIEW block diagram with a single SignalExpress Express VI, as shown in the following figure.

Figure 1: SignalExpress Express VI

When does LabVIEW SignalExpress generate this single Express VI instead of an individual Express VI for each step? What can I do with this Express VI?

Solution:
The underlying code for this Express VI cannot be opened up in the same manner as a normal LabVIEW subVI or Express VI. Trying to do so will only open the LabVIEW SignalExpress project that was used for the code generation. The VI can still be built into an executable, but you will be limited in the front panel controls that can interact with the SignalExpress Express VI. For more information about potential problems involved with building the SignalExpress Express VI into an executable, refer to KnowledgeBase 490I589S: Problems with Deploying LabVIEW Code Generated from LabVIEW SignalExpress Project (see Related Links at the bottom of the page).

LabVIEW SignalExpress generates LabVIEW code with a single Express VI, as shown in Figure 1, under the following conditions:

The project performs analog or digital output with the DAQmx Generate step.
The project contains multiple, synchronized DAQmx Acquire steps.

For example, if a project contains one DAQmx Acquire step that acquires from dev1/ai0 and another DAQmx Acquire step that acquires from dev2/ai2, and you synchronize the steps by sharing the sample clock, the generated LabVIEW code contains a single SignaExpress Express VI.
- Projects that contain DAQmx Acquire and Modular Instrument or IVI Acquire steps that you synchronize by sharing the sample clock also generate LabVIEW code containing the Express VI shown in Figure 1.
- Code generation works as expected in projects with a single DAQmx Acquire step that uses channel expansion to synchronize multiple devices.
The project contains a DAQmx step that is configured to wait on, or be waited on by, another hardware acquistion step.

For example, consider a project containing a DAQmx Acquire step, followed by a NI-DMM/Switch Acquire step. You can use the Execution Control page of the Step Setup tab for the NI-DMM/Switch Acquire step to configure the step to wait for the DAQmx Acquire step to execute, as shown in Figure 2.

Figure 2: Execution Control Tab

The reverse situation also results in the Express VI in Figure 1 being generated in LabVIEW.

Note: This problem only occurs if you use a DAQmx step. It does not occure with other hardware steps.

The project contains steps with specified pre- or post-execution delays.
The project contains a hardware step for which you do not select any channels.
The project contains a Trigger step.
The project contains hardware acquistion or generation steps in a Conditional Repeat loop.
The project contains parameters you are sweeping using the Sweep step.
The project contains DAQmx Acquire steps with multiple analog input types, such as temperature and voltage input channels in a single DAQmx Acquire step.
The project uses logging or recording features. This includes any feature found on the Recording Options tab. (Ex: Alarms, Start Conditions and Stop Condtiions, and Signals to Record)
You are generating code to versions of LabVIEW older than LabVIEW 8.20.

- SignalExpressExpressVI.jpg

- ExecutionControlTab.jpg

Report Date: 03/30/2007
Last Updated: 08/05/2008
Document ID: 47TGOST7

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